Wave guides



1958 E. s. BALlA N 2,860,311

WAVE GUIDES Fild April 16, 1956 ANTENNA 2 F'GJ.

"a E a\ E ROTARY 7 CONNECTION DUPLEXER TRANSMITTER PRESSURIZER DEHYDRATORS RECEIVER FIG.4.

93 v INVENTORI EDWARD s. BALIAN,

HIS AGENT.

United States Paten WAVE GUIDES Edward S. Balian, North Syracuse, N. Y., assiguor to General Electric Company, a corporation of New York Application April 16, 1956, Serial No. 578,230

1 Claim. (Cl. 333-98) This invention relates to wave guides and more particularly to a simplified construction of pressurized wave guide.

In recent years peak power requirements have increased in equipments operating at high frequencies, for example, radar equipments. With the increase in peak power requirements, pressurized wave guide has become a necessity to prevent electrical breakdown of the dielectric at these high powers. In such wave guide, particularly rectangular wave guide used widely in radar equipments, the pressurized dielectric medium has created the problem of wall support, since the internal pressure applied force to the walls. This force often causes the walls of wave guide, particularly the wide wall of rectangular wave guide to bulge beyond design tolerance and in many cases causes mechanical failure of the wall. To prevent such bulging, the prior art has seen fit to clamp the wave guide externally and to use extremely thick walled guide. Such solutions have increased the weight, size, and complexity of the wave guide and the utilizing equipments.

Accordingly, it is one object of my invention to obviate these difiiculties in pressurized wave guide.

Another object of my invention is to provide a pressurized wave guide of minimum weight, size, and complexity.

A further object of my invention is to provide a pressurized wave guide for carrying high power R. F. energy without distortion of the side walls due to pressurization.

A further object of my invention is to provide a wave guide having increased strength, either as a beam or a column.

A further object of my invention is to provide an improved wave guide.

To this end there is provided, in. accordance with one embodiment of the present invention, a wave guide surrounded by a cylinder. The space between the cylinder and the wave guide is pressurized to the same pressure as- In this manner, the. external and internal pressures on the wave guide walls that existing within the wave guide.

can be balanced and bulging of the wave guide wall out of tolerance is eliminated while still having a. dielectric.

under pressure for transmitting a large power without electrical breakdown.

In another embodiment, air passages are provided between the interior of the wave guide and the space between the wave guide and'the cylinder. In this embodiment, the cylinder withstands the force of the pressurized dielectric and no force is applied to the wave guide walls.

The features of my inventionwhich are believed to be novel are set forth with particularity in the appended My invention itself, however, both. as to its organization and method of operation, together with claims.

further objects and advantages thereof, may: best be understood by reference to the following description taken inconnection with the accompanyingdrawings, in.

which:

2,860,3ll Patented Nov. 11., 1958 Figure 1 is a partly cross-sectioned, diagrammatic view of a typical installation in accordance with the present invention;

Figure 2 is a perspective view of a rectangular wave guide in accordance with the present invention;

Figure 3 is a cross-sectional view of one junction of two wave guides employable in the installation of Figure 1;

Figure 4 is a cross-sectional view of a modification of the junction shown in Figure 3;

Figure 5 is a plan view of a gasket adaptable for use with the junction shown in Figure 4;

Figure 6 is a cross-section of a modification of the wave guide of Figure 2;

Figure 7 is a cross-section of a modification of the wave guide shown in Figure 2.

Fig. 8 is a cross section of the wave guide of Fig. 7 taken at line 8-8; and

Fig. 9 illustrates a cross section of a unitary structure for a wave guide of the type disclosed.

In Figure 1, there is shown a typical installation of the present invention with a transmitter 1 which is adapted to generate electromagnetic waves of the high power necessary for modern radar.

The generated waves are applied to antenna 2 through wave guide 3, duplexer 4, wave guides 6, rotary connection 7, and wave guide 8.

The antenna is adapted to launch the waves into space for object detection and also to receive waves, such as reflections of the launched waves by detected objects.

I The returned waves are transmitted to the receiver 9 over wave guides 8 and 6, rotary connection 7, duplexer 4 and wave guide 10.

The duplexer operates in conventional fashion to isolate the receiver from high power waves generated by transmitter 1 while applying the relatively low power waves received by antenna 2 to the receiver 9.

The rotary connection provides a continuous electric path for passage of electrical waves while allowing mechanical movement of the antenna such as rotation of nutation. V

The dimensions of the wave guides employed for wave' transmission depends upon the characteristics of the generated waves.

In order for the installation of Figure 1 to carry the power required by modern radar, it is necessary to The pipe casing surrounds the wave guide 14. Air passages 15 communicate with the inside of the wave guide to provide a dielectirc of proper pressure without applying force to the wave guide walls.

It should be obvious to those skilled in the art that both wave guides 8 and 10 may be similarly included within a pipe section.

carry high power. However, as will be apparent to those skilled in the art, the usual horn construction may not require pressurization, and, when needed, the horn isoften sufficiently strong to be pressurized without external support. In such cases, a solid low loss dielectric window, such as vycor glass quartz, can be employed atthe junction between pressurized and unpressurized sections.

The duplexer is usually constructed as a casting having reasonably thick walls. and generally requiresno additional support for the pressurization of the dielectric within it. Therefore, the duplexer need not. be contained within a pipe-like structure. It should be obvious to those skilled in the art that in some embodiments, the

However, the wave guide 10- rarely requires pressurization because of the relatively low power of the energy carried. Wave guide 8 does duplexer can be contained within a pipe-like structure. The operation of the wave guide as shown in Figure 1 may best be understood by reference to Figure 2.

In Figure 2 is shown a rectangular wave guide 21 contained within a hollow cylindricalpipe 22. Apertures 23 communicate between the interior of the rectangular wave guide 21 and the interior of the hollow pipe 22 to maintain the same pressure within both cavities. In this manner, the internal pressure created by the pressurized dielectric is supported by the walls of the cylindrical pipe 22. The cylinder configuration can maintain a much higher pressure differential without distortion than can the rectangular wave guide. 1

For example in a current system utilizing 25 pounds per square inch dielectric pressure, a rectangular wave guide having walls formed of inch thick metal was necessary to limit the wall distortion to allowable tolerance limits. By contrast, a wall thickness of only $4 of an inch would be required in a cylindrical configuration to withstand this internal pressure. A thin pipe section was, of course, not used because of the possibility of crushing with such a thin wall. However, this example does show the relative thickness of metal necessary to provide the same structural rigidity. This becomes particularly important as higher pressures are reached in equipments necessitating higher power transmittal. Such equipments shall require dielectric pressures of pounds per square inch and higher.

The apertures 23 are placed in such locations as to provide air passages between the interior of the wave guide and the space between the wave guide and pipe walls without altering the electrical characteristics of the wave guide transmission path. It should be obvious to those skilled in the art that the wave guide and the space around the wave guide can be pressurized to the same pressure to support the waveguide when communieating apertures cannot be used.

, The wave guide sections must be joined to provide continuous electrical contact and pressure-tight sealing. Such a junction is shown in Figure 3. In Figure 3 is shown two abutting guide lengths 31 and 32. The surrounding pipe sections 33 and 34 carry a flange 35 and 36 respectively at the inter-face. The flange face is machined below the end of the wave guide 31 so that the ends of the Wave guides 31 and 32 'will be put into intimate contact when the sections are joined together. In one embodi ment, it was found that a machining of the face of the flange 0.002 inch below the end of wave guide 31 was practicable. An 0 ring 37 is provided to form a pressure tight seal when the flanges are drawn together by bolt 39 and nut 40.

An alternative junction is shown in Figure 4. In such a junction the wave guide 31 and flange 35 are machined flush. A gasket 41 is placed between sections. The gasket supplies pressure sealing means as well as supplying electrical contact between the two wave guide sections.

Figure 5 shows a plan view of such a gasket. The diameter of the gasket shown matches the diameter of the flange, and holes 51 are provided for passage of the securing bolts through the flanges. The aperture 52 is dimensioned to match the periphery of the wave guide section in order to contact both abutting sections without introducing electrical discontinuities into the wave guide. In some applications, it has been found advisable to provide a knurled section along this periphery to ensure good electric contact.

It is, of'course, feasible to construct this wave guide as a rectangular wave guide and a separate cylindrical pipe surrounding said wave guide. In such construction however, the wave guide must be solidly atfixed to the pipe to prevent relative lateral motion therebetween at the junction. A method for securing the wave guide to the pipe section is shown in Figure 6 wherein the wave guide 61 is secured to the pipe 62 by means of a boss 63 on the 4 wave guide 61. The boss is threaded and a bolt 64 extending through the pipe wall to the wave guide is tightened in the threaded section. A washer 65, such as a combination Q ring-metal washer, insures a pressuretight seal at the opening through which bolt 64 extends.

Another method of securing the wave guide to the pipe would be to drill small holes in the pipe which would be coincident with the wave guide corners. By plug welding the holes, the wave guide would be rigidly attached to the pipe and the pipe would be pressure sealed.

Still another method of securing the wave guide to the pipe is shown in Figures 7 and 8, wherein the wave guide 71 is welded to a flange 72 having an aperture corresponding to the wave guide cross section. The pipe section '73 is welded to the flange to hold the pipe concentric with the wave guide section. At a junction of two wave guide sections, the flange faces 74 provide electrical continuity. The O-ring 75 provides a pressure-tight seal when the flanges 72 are secured together by bolts '76.

To enable welding of the wave guide to the flange prior to completely enveloping the wave guide by the pipe, a sleeve 77 is provided on one side of the junction. The sleeve can he slid along the pipe while welding the waveguide to the flange. Then the sleeve can be wound into. place and welded to the flange and pipe section as shown by billets 78. Pressure identity is maintained by aperture 79.

The construction of pressurized wave guide in accordance with this invention, is adaptable to any size wave guide with only minor modifications apparent to those skilled in the art. For example, in Figure 9 is shown a construction found advantageous for use with a small wave guide.

In Figure 9 is shown a rectangular wave guide 91. having a pressurized dielectric 92 surrounded by a cylinder 93. The area 94 above the wide wall faces of the wave guide maintained at the same pressure as that of the dielectric in the wave guide by the communicating apertures 95. The narrow wall faces are supported by solid material 96 between the wall and the cylinder 93. Such construction is merely a constructional detail for convenience, particularly adaptable for extrusion processing. While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

A waveguide adapted to contain a pressurized fluid dielectric for carrying electromagnetic energy at high power levels comprising, a rectangular metallic waveguide, a cylindrical metallic pipe, said rectanguar waveguide be-' ing supportably contained within said pipe and having a protruding portion extending beyond a first end of said pipe; a plurality of apertures in said rectangular waveguide; first and second annular flange members attached to the two ends respectively of said rectangular waveguide; a sleeve member slidably mounted on said pipe for displacement during welding of its associated wave guide section to its associated flange and protruding beyond said first end of said pipe so as to surround said protruding portion of said waveguide, said sleeve member being subsequently welded to a first of said annular flange members, the second of said annular flange mem-' bers being welded to the second end of said pipe; each of said annular flange members having a substantially flat exterior surface with an annular recess therein adapted to receive pressure retaining means when a plurality of said waveguides are clamped together to form a wave transmission line.

References Cited in the file of this patent UNITED STATES PATENTS Aamodt Nov. 11, 1947 

